Lifting jack



ly 23 4 v A. JACKSON 2,404, 17

' LIFTING JACK Filed July 31, 1945 INVENTQR ALEX/s CIA (KS o/v ahf mw ATTORNEY cylinder being closed.

raised such as an axle of an automotive vehicle Patented July 23, 1946 UNITED STATES PATENT OFFICE LIFTING JAGK Alexis Jackson, Westport, Conn assign'or to vatlim S. Mak'arofi, New York, N. Y.

Application July 31, 1943, jSerial-No. 496,883

6 Claims. (01. 254--s) My invention relates to lifting jacks and has particular reference to portable jacks for lifting various objects, and more particularly to jacks operated by a fluid under pressure.

My invention has for its object to provide a lifting jack which can be used for lifting such objects as automotive vehicles from relatively low elevation, as, for instance, when a tire on the vehicle wheel is fiat and there is very little room under the axle to place a lifting jack therein. 1

In my United States Patent No; 2,230,250, issued February 4, 1941-, I disclosed a. lifting jack of "a similar construction, which can be placed under a low positioned axle of an automotive vehicle. I'have found, however, that automotive vehicles often have projecting parts, such as bumpers, etc., extending far to the rear of the axle so that the jack must have sufficient low clearance practically throughout its full length. Itwas found "that certain 'parts of the jack disclosed in the foregoing patent interfere with 'the insertion of the jack under long low-hung bodies.

In my present invention 1 have modified the construction by moving the operating cylinder to the rear of the lifting arms, and eliminating other connecting parts which may interfere with the insertion of the jack in its place.

My invention is more fully described in the accompanying specification and drawing, in which:

Fig. 1 is an elevational view of my jack in an inoperative position with the lifting-arm lowered;

Fig. 2 is a similar view of the jack in an operative position with ,the lifting arm raised;

Fig. 3 is a sectional detail view of the operating cylinder; and

Fig. 4 is1a top plan'view of the jack.

My lifting jack consists of a frameformed of apair of arms I connected at the front by an axle 2 with supporting wheelss. The rear ends of the arms l, are pivotally mounted on trunnions 4 extending from a reinforcing ring 5 on the open lower end of a cylinder 6, the upper end of the The frame arms are rotatively mounted on a shaft l which also mounts a lifting member consisting of a pair of lifting arms 8 with hooks 9 at the front ends for engaging an object to be (not shown). The rear ends of the lifting arms ate pivotally mountedonarod 0 passing through the lower end of a tubular piston ll sliding in. thecylinder 6 Theends of the rod in extend beyond the end-s of the-frame arms fl and mount supporting wheels 12. The lifting arms are connected together as by a rod 'or tube l3.

Piston H is provided with a sealing disc [4, Fig. 3, made of leather or other 's'uitablematerial, tightly fitted in the cylinder and fastened to the closed top of 't'he'ipiston as by a bolt1f5.

A valve '16 is provided on top of the cylinder for admitting compressed air into the cylinder,- the valve being preferably of a type used with inner tubes of automobile tires so that thesame air hose {which is 'used "for pumping tires "can be used "to operate by lifting jack. The valve is of a one-way type, 1. e., for admitting the air but not for discharging the same. For the latter purpose api'pe l1 is'p'rovided extending from the closed "top of the piston l'l inside the piston and con ected with an outer nipple l'8 to which a flexible hose I 9 "is attached. The hose is in mm cohnected with a pipe 20 supported inside a hollow'rod 2| pivotally attached to a lug '22 extending from the lower end of -the piston, the upper end of the rod having a hand'l'e'23fin the form of a cross-bar; Avalve 24 is provided at the top of the pipe 20 for releasing the air from the piston w'henit is desired to lowertl'fe lifting arms. The handle can be used for 'moving the "lifting jack around and "for "placin'g'i't 'in "an operative position under an automobile.

Forlocki'ngthe lifting "a'rmsin a raisedpos'ition as shown in Fig. 'a the'piston 11 has ho1es25tfor a lock'in'g'rod7'2'6 which, when in's'erte'dl'n a corresponumgnm prevent the cyunaer fi' frorn sliding down overthe piston. The red, when 'no'tin use, is heldin a'soket2'l at the 'side'of'the cylin der fi as shown in Fig. 1. V

Distance fromt'he' rear'en'ds of theIlift'ing arms to the common shaft '1 'iisconsiderably, smaller than the distance from the's'haft "I to the'ffiont ends of the lifting arms so that -the arms can 'be raised to a considerable height with a relatively small travel of the piston. I l I My lifting jack has an important advantageln that both sets of arms, :-frame and lifting, Ilie very low as is shown inFigf-l so that the'fjac k can be moved under a ver'ylo'w' vehiclejwith'out interference with long overhanging parts 'sunas bumpers, trunk's spa're 't'ire's, etc. P 1

It will be noted, particularly from '1, that the motor is inclined upwardly and away from the frontjend of the jack when in collapsed conscissors and'that this pivot shaft divides these motor is only slightly greater than the length of the rear levers; that the lifting member occupies a, position nearer the vertical and the frame occupies a position near the horizontal when the jack is in its highest raised position. It will also be seen that the distance between wheels 3 and I2, defining the wheel or supporting base contracts comparatively little as the jack is raised, I

means to movably support the front end of the It will be seen from a comparison of Figs. 1 and 2 1' that because of this dissymmetry of construction the stability of the jack changes from the position of relatively small stability shown in Fig. 1, to the position of relatively great stability shownin Fig. 2, when the jack is raised from its collapsed position to its highest'position.

It is understood that the cylinder may be of any isuitable type for operation by compressed air or other elastic fluid, also to be operated by an incompressible fluid such as oil, or by combination of the two fluids.

It is understood that my lifting jack may be further modified without departing from the spirit of the invention, as set forth in the appended .claims. g I

I claim as my invention: a

l. A lifting jack comprising a frame; means to movably support the front end of the frame on the ground, the rear end of the. frame being adapted to be raised from the gro'und; a lifting motor consisting of two telescopic members, one

telescopic member being pivotally connected to the rear end of the frame, the other telescopic member being pivotally connected to the rear end of the lifting member, one telescopic member being in the form 'of'a cylinder closed at the outer being pivoted to the rear end of said lifting arms, said cylinder being disposed above said piston, said cylinder having its upper end closed and its lower end located between the rear ends of said frame arms and pivoted thereto, means for supplying said motor with fluid for causing the piston and cylinder to move apart thereby raising the frontendof said lifting member, and causing it to move from a position of'relatively low stability to a position of relatively great stability.

3. In a scissors type, high lift jack, a frame;

frame on a supporting surface, the rear end of said frame being adapted to be raised from said supporting surface, a lifting member pivotally connected to the frame by a pivoting member which divides said frame and lifting member into relatively short rear levers and relatively long front levers, the front end of the lifting member being adapted to engage the load to be lifted, means for movably supporting the rear end of said lifting member on said supporting surface, a motor comprising expansible members pivotally connected to the rear ends of said'frame and lifting member for moving said rear ends apart, said motor members being expansible from a position representing a substantially collapsed condition of the jackto a distance at least equal to the length of said shorter levers and representing a condition where said lifting member is nearer the.

vertical than horizontal while said frame member is nearer horizontal than vertical. 7

4; In a scissorstype, high lift'jack, a frame,

alifting member," pivot means connecting said frame and lifting member, said pivot means dividing said frame and lifting member into relatively long front levers and relatively short rear levers, devices for movably supporting the rear end of said lifting member and the front end of said frame on a supporting surface, the front end of the lifting member having a load-elevating portion located adjacent the front end of the frame when the jack is collapsed so that the jack has and open at theinner end; the other telescopic member being in the form of a piston slidably fitted in the cylinder; a one-way valve on the cylinder for admitting a fluid under pressure in the cylinder thereby causingjthe lifting member to be raised; a handle extending from the rear end ofthe motor; a pipe extending from the handle into the cylinder; and a manually operablevalve;

on the pipe for, releasing the fluid from the cylinder thereby allowing the lifting member to be lowered. I

2. In a lifting jack for lifting one end of an automotive vehicle high off a supporting surface, said jack comprising a frame having a pair of spaced arms, a cross-member secured to said arms near their front ends, wheels journaled on said frame to 'movably support the front end of the frame on the supporting surface, the rear end of the frame being adapted to be raised from the supporting surface, a lifting member comprising spaced arms positioned within said frame arms, 7

a horizontal pivoting member connecting said frame arms and lifting arms, said pivoting member dividing said frame and lifting member into relatively long front levers and relatively short rear levers, the front end of the lifting member being adapted to engage one end of said automotivevehicle for lifting the same, Wheels on the relatively low stability when in such collapsed condition, a relatively short stroke motor comprising movable members pivotally connected to the rear ends of said lifting member and frame for elevating the latter, whereby the stroke of said motor raises said load-elevating portion proportionally more than the stroke of said motor'and substantially increases the stability of said jack from its condition of relatively low stability to a condition of'relatively great stability. L

5; In a scissors type, high lift jack, a frame, a lifting member, pivot means connecting said frame and lifting member, said pivot means dividing said frame and lifting member into relatively long front levers and relatively shortrear levers,

devices for movably supporting the rear end of said lifting member and the front end of said frame on a supporting surface, the front end of V the lifting member having a load-elevating por-- tion located adjacent the front end of the frame when thejack is collapsed so that the jack has relatively small stability when in low position, a relatively short stroke motor operating between the rear ends of said lifting member and frame for elevating the latter, the dissymmetrical arrangement of said pivot means causing the elevating movement of said motor to raise said loadelevating portion proportionally more than the strcke of said motor, and said frame toretain a position generally nearer the horizontal than vertical, and said load-elevating portion to swing further within the supporting base defined by said 5 supporting devices to give the jack relatively great stability when raised.

6. In a scissors type jack for lifting an automobile, a frame, a lifting member, pivot devices connecting said frame and lifting member, said pivot devices dividing said frame and lifting member into relatively long front levers and relatively short rear levers, the front end of the lifting member having a load elevating portion adapted to engage the automobile, wheeling devices for movably supporting the rear end of said lifting memher and the front end of said frame on a supporting surface, an upright motor comprising movable 6 members having pivot connections with the rear ends of said lifting member and frame for elevating the latter; said motor pivot connections being so located that the axis of said motor is inclined upwardly and away from the front of the jack, and said load elevating portion having such an extended position adjacent the front wheeling devices, as to provide increased bumper clearance when the jack is collapsed, such dissymmetrical positioning of said pivot devices substantially increasing the stability of the jack when in raised position.

ALEXIS JACKSON. 

